Decoupled Chinese Loess Plateau Dust Deposition and Asian Aridification at Millennial and Tens of Millennial Timescales

Abstract

Asian climate is controlled by the Asian monsoons and westerlies. The Asian monsoons bring at times extensive moisture from the Indian Ocean and Pacific Ocean to southern and eastern Asia during summer. By contrast, the westerlies have limited ability to bring moisture to central Asia and western China due to the long distance to major moisture sources in the Atlantic Ocean (Figure 1). As such, westerlies-dominated (inland) Asia is generally dry, with current annual precipitation rarely exceeding 250 mm and prevailing arid to hyper-arid conditions, while monsoonal Asia tends to experience dry sub-humid to humid conditions. At present, the boundary between monsoonal versus westerlies dominated Asia, that is, the southeastern boundary of arid inland Asia, lies at the Asian summer monsoon northwestern limit (Figure 1, Chen et al., 2008), though this boundary may have shifted between glacials and interglacials (Yang et al., 2015).The Chinese Loess Plateau (CLP) lies within the current monsoonal Asia (Figure 1) and has the thickest loess deposits in Asia. These deposits are invaluable paleoclimate archives allowing reconstruction of East Asian monsoon and inland Asian aridification history back to 25-22 Ma (Guo et al., 2002;Porter, 2001;Qiang et al., 2011;Sun et al., 2010). In particular, loess magnetic parameters and grain-size have been widely used to infer East Asian summer and winter monsoon intensities since the Miocene (An et al., 1991;Lu et al., 2000;Sun et al., 2016). By contrast, dust accumulation rate (DAR) on the CLP has been suggested to indicate the degree of inland Asian aridification or desertification, based on the assumption that the vast deserts and gobi areas in interior Asia act as the CLP's primary dust source regions (

From Desiccation to Re‐Integration of the Yellow River Since the Last Glaciation

“…The erosion of the Chinese Loess Plateau was greatly attenuated during times of lower runoff and without anthropogenic interference (Deng & Yuan, 2001; Sang et al., 2004), which could be explained by the desiccation of the upper Yellow River leading to (a) reduced sediment discharge farther downstream into the ocean during dry‐cold periods, and (b) exposure of floodplains and lacustrine sediments that could act as sources for loess areas downwind (Nie et al., 2015). The aforementioned (as shown in Figure 2 and described in Section 4.1) climate‐river desiccation feedbacks across glacial‐interglacial cycles assist in better elucidating the source‐to‐sink relationship between the Chinese Loess Plateau and the Yellow River (Deng & Yuan, 2001; Peng et al., 2022). That is, despite the fact that Yellow River floodplains are not major sources of windblown detritus for the downwind North Pacific Ocean today (Zdanowicz et al., 2006), during glacial periods, these areas could be major dust sources due to persistent exposure to the air.…”

Provenance of Aeolian Dust Revealed by (234U/238U) Activity Ratios in Cryoconites From High‐Altitude Glaciers in Western China and Its Transport and Settlement Mechanisms

“…According to numerous studies, dust transported in northwest China had a homogenous geochemical signature, compatible with dust emitted by the northern TP (J. Licht et al, 2016;Nie et al, 2015;Peng et al, 2022). The similar geochemical features made it difficult to make a more detailed distinction of the sources.…”

Spatial Source Contribution and Interannual Variation in Deposition of Dust Aerosols Over the Chinese Loess Plateau

“…We go beyond the usual 10 μm threshold to simulate dust particles of 15–20 μm (referred to as "super‐coarse dust") to contrast fine dust particles (1.7–2.5 μm) in order to tell whether the deposition of fine dust occurs under the same climate conditions as that of super‐coarse dust and whether the source regions are the same. We chose to study the interannual variation in the dust deposition rate over the CLP because we are interested in understanding the processes responsible for the changes in loess Mass Accumulation Rate, with implications for identifying the factors that could be driving the changes that have occurred on longer time scales (F. Peng et al., 2022).…”